Anticipated Impacts on Veteran's Healthcare: With wars in Iraq and Afghanistan, there is a growing number of Veterans with posttraumatic stress disorder (PTSD). Traditional PTSD treatments are not beneficial to all Veterans, thus creating a need for new approaches. Currently, there are few complementary therapies that have been studied as first-line treatments for PTSD. We have developed and tested a method of portable, concentrative meditation called the Mantram Repetition Program (MRP) in Veterans with PTSD and found it effective for symptom management when offered as an adjunct to usual care (i.e., medication and case management). If this meditation-based program is found effective as a first-line treatment for PTSD, it could fill a gap for those Veterans for whom traditional treatments fail. Project Background: We have conducted several pilot studies including a randomized controlled trial on the feasibility and acceptability of a 6-week (90 minutes per week) MRP in 146 Veterans with chronic PTSD from military-related trauma. Those assigned to usual care plus the MRP demonstrated significant decreases in self- reported PTSD compared to usual care controls. At post-intervention, 30% of those in the MRP compared to 14% of those in the usual care condition, no longer met diagnostic criteria of PTSD. Qualitative interviews at 3- months post-treatment revealed that MRP was used most frequently to regulate disruptive emotional and behavioral responses (e.g., manage irritable, angry outbursts), tolerate distress (e.g., calm down, relax, reduce anxiety/panic), and interrupt obsessive thoughts about negative events. These findings suggest that the MRP has promise as a stand-alone treatment to help Veterans manage their symptoms of PTSD, but this research is needed to control for the effects of group support. Project Objectives: The goal of this study is to evaluate the treatment efficacy of the MRP as a first-line, stand-alone treatment for PTSD compared to an attention control consisting of Present Centered Group Therapy (PCGT) in a representative sample of Veterans with PTSD. Project Methods: This study will use a prospective, two-site, randomized clinical trial design comparing two groups (MRP and PCGT) at three time points (pre-intervention, post-intervention and 16-week follow-up). Outpatient Veterans (N=324) diagnosed with PTSD will be recruited and randomly assigned to either an 8- week MRP (n=162) or 8-week PCGT control (n=162). PTSD will be measured using Clinician Administered PTSD Scale (CAPS) and PTSD checklist-military (PCL-M). Secondary outcomes will include measures of psychological distress (depression, insomnia, anger) and quality of life and spiritual wellbeing.